1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements routines for folding instructions into simpler forms
11 // that do not require creating new instructions. This does constant folding
12 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
15 // simplified: This is usually true and assuming it simplifies the logic (if
16 // they have not been simplified then results are correct but maybe suboptimal).
18 //===----------------------------------------------------------------------===//
20 #define DEBUG_TYPE "instsimplify"
21 #include "llvm/GlobalAlias.h"
22 #include "llvm/Operator.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/Analysis/InstructionSimplify.h"
25 #include "llvm/Analysis/AliasAnalysis.h"
26 #include "llvm/Analysis/ConstantFolding.h"
27 #include "llvm/Analysis/Dominators.h"
28 #include "llvm/Analysis/ValueTracking.h"
29 #include "llvm/Support/ConstantRange.h"
30 #include "llvm/Support/GetElementPtrTypeIterator.h"
31 #include "llvm/Support/PatternMatch.h"
32 #include "llvm/Support/ValueHandle.h"
33 #include "llvm/Target/TargetData.h"
35 using namespace llvm::PatternMatch;
37 enum { RecursionLimit = 3 };
39 STATISTIC(NumExpand, "Number of expansions");
40 STATISTIC(NumFactor , "Number of factorizations");
41 STATISTIC(NumReassoc, "Number of reassociations");
45 const TargetLibraryInfo *TLI;
46 const DominatorTree *DT;
48 Query(const TargetData *td, const TargetLibraryInfo *tli,
49 const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {};
52 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
53 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
55 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
57 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
58 static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
59 static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
61 /// getFalse - For a boolean type, or a vector of boolean type, return false, or
62 /// a vector with every element false, as appropriate for the type.
63 static Constant *getFalse(Type *Ty) {
64 assert(Ty->getScalarType()->isIntegerTy(1) &&
65 "Expected i1 type or a vector of i1!");
66 return Constant::getNullValue(Ty);
69 /// getTrue - For a boolean type, or a vector of boolean type, return true, or
70 /// a vector with every element true, as appropriate for the type.
71 static Constant *getTrue(Type *Ty) {
72 assert(Ty->getScalarType()->isIntegerTy(1) &&
73 "Expected i1 type or a vector of i1!");
74 return Constant::getAllOnesValue(Ty);
77 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
78 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
80 CmpInst *Cmp = dyn_cast<CmpInst>(V);
83 CmpInst::Predicate CPred = Cmp->getPredicate();
84 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
85 if (CPred == Pred && CLHS == LHS && CRHS == RHS)
87 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
91 /// ValueDominatesPHI - Does the given value dominate the specified phi node?
92 static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
93 Instruction *I = dyn_cast<Instruction>(V);
95 // Arguments and constants dominate all instructions.
98 // If we have a DominatorTree then do a precise test.
100 if (!DT->isReachableFromEntry(P->getParent()))
102 if (!DT->isReachableFromEntry(I->getParent()))
104 return DT->dominates(I, P);
107 // Otherwise, if the instruction is in the entry block, and is not an invoke,
108 // then it obviously dominates all phi nodes.
109 if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
116 /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
117 /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
118 /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
119 /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
120 /// Returns the simplified value, or null if no simplification was performed.
121 static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
122 unsigned OpcToExpand, const Query &Q,
123 unsigned MaxRecurse) {
124 Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
125 // Recursion is always used, so bail out at once if we already hit the limit.
129 // Check whether the expression has the form "(A op' B) op C".
130 if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
131 if (Op0->getOpcode() == OpcodeToExpand) {
132 // It does! Try turning it into "(A op C) op' (B op C)".
133 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
134 // Do "A op C" and "B op C" both simplify?
135 if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
136 if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
137 // They do! Return "L op' R" if it simplifies or is already available.
138 // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
139 if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
140 && L == B && R == A)) {
144 // Otherwise return "L op' R" if it simplifies.
145 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
152 // Check whether the expression has the form "A op (B op' C)".
153 if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
154 if (Op1->getOpcode() == OpcodeToExpand) {
155 // It does! Try turning it into "(A op B) op' (A op C)".
156 Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
157 // Do "A op B" and "A op C" both simplify?
158 if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
159 if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
160 // They do! Return "L op' R" if it simplifies or is already available.
161 // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
162 if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
163 && L == C && R == B)) {
167 // Otherwise return "L op' R" if it simplifies.
168 if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
178 /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
179 /// using the operation OpCodeToExtract. For example, when Opcode is Add and
180 /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
181 /// Returns the simplified value, or null if no simplification was performed.
182 static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
183 unsigned OpcToExtract, const Query &Q,
184 unsigned MaxRecurse) {
185 Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
186 // Recursion is always used, so bail out at once if we already hit the limit.
190 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
191 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
193 if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
194 !Op1 || Op1->getOpcode() != OpcodeToExtract)
197 // The expression has the form "(A op' B) op (C op' D)".
198 Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
199 Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
201 // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
202 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
203 // commutative case, "(A op' B) op (C op' A)"?
204 if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
205 Value *DD = A == C ? D : C;
206 // Form "A op' (B op DD)" if it simplifies completely.
207 // Does "B op DD" simplify?
208 if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) {
209 // It does! Return "A op' V" if it simplifies or is already available.
210 // If V equals B then "A op' V" is just the LHS. If V equals DD then
211 // "A op' V" is just the RHS.
212 if (V == B || V == DD) {
214 return V == B ? LHS : RHS;
216 // Otherwise return "A op' V" if it simplifies.
217 if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) {
224 // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
225 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
226 // commutative case, "(A op' B) op (B op' D)"?
227 if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
228 Value *CC = B == D ? C : D;
229 // Form "(A op CC) op' B" if it simplifies completely..
230 // Does "A op CC" simplify?
231 if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) {
232 // It does! Return "V op' B" if it simplifies or is already available.
233 // If V equals A then "V op' B" is just the LHS. If V equals CC then
234 // "V op' B" is just the RHS.
235 if (V == A || V == CC) {
237 return V == A ? LHS : RHS;
239 // Otherwise return "V op' B" if it simplifies.
240 if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) {
250 /// SimplifyAssociativeBinOp - Generic simplifications for associative binary
251 /// operations. Returns the simpler value, or null if none was found.
252 static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
253 const Query &Q, unsigned MaxRecurse) {
254 Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
255 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
257 // Recursion is always used, so bail out at once if we already hit the limit.
261 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
262 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
264 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
265 if (Op0 && Op0->getOpcode() == Opcode) {
266 Value *A = Op0->getOperand(0);
267 Value *B = Op0->getOperand(1);
270 // Does "B op C" simplify?
271 if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
272 // It does! Return "A op V" if it simplifies or is already available.
273 // If V equals B then "A op V" is just the LHS.
274 if (V == B) return LHS;
275 // Otherwise return "A op V" if it simplifies.
276 if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
283 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
284 if (Op1 && Op1->getOpcode() == Opcode) {
286 Value *B = Op1->getOperand(0);
287 Value *C = Op1->getOperand(1);
289 // Does "A op B" simplify?
290 if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
291 // It does! Return "V op C" if it simplifies or is already available.
292 // If V equals B then "V op C" is just the RHS.
293 if (V == B) return RHS;
294 // Otherwise return "V op C" if it simplifies.
295 if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
302 // The remaining transforms require commutativity as well as associativity.
303 if (!Instruction::isCommutative(Opcode))
306 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
307 if (Op0 && Op0->getOpcode() == Opcode) {
308 Value *A = Op0->getOperand(0);
309 Value *B = Op0->getOperand(1);
312 // Does "C op A" simplify?
313 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
314 // It does! Return "V op B" if it simplifies or is already available.
315 // If V equals A then "V op B" is just the LHS.
316 if (V == A) return LHS;
317 // Otherwise return "V op B" if it simplifies.
318 if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
325 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
326 if (Op1 && Op1->getOpcode() == Opcode) {
328 Value *B = Op1->getOperand(0);
329 Value *C = Op1->getOperand(1);
331 // Does "C op A" simplify?
332 if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
333 // It does! Return "B op V" if it simplifies or is already available.
334 // If V equals C then "B op V" is just the RHS.
335 if (V == C) return RHS;
336 // Otherwise return "B op V" if it simplifies.
337 if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
347 /// ThreadBinOpOverSelect - In the case of a binary operation with a select
348 /// instruction as an operand, try to simplify the binop by seeing whether
349 /// evaluating it on both branches of the select results in the same value.
350 /// Returns the common value if so, otherwise returns null.
351 static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
352 const Query &Q, unsigned MaxRecurse) {
353 // Recursion is always used, so bail out at once if we already hit the limit.
358 if (isa<SelectInst>(LHS)) {
359 SI = cast<SelectInst>(LHS);
361 assert(isa<SelectInst>(RHS) && "No select instruction operand!");
362 SI = cast<SelectInst>(RHS);
365 // Evaluate the BinOp on the true and false branches of the select.
369 TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
370 FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
372 TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
373 FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
376 // If they simplified to the same value, then return the common value.
377 // If they both failed to simplify then return null.
381 // If one branch simplified to undef, return the other one.
382 if (TV && isa<UndefValue>(TV))
384 if (FV && isa<UndefValue>(FV))
387 // If applying the operation did not change the true and false select values,
388 // then the result of the binop is the select itself.
389 if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
392 // If one branch simplified and the other did not, and the simplified
393 // value is equal to the unsimplified one, return the simplified value.
394 // For example, select (cond, X, X & Z) & Z -> X & Z.
395 if ((FV && !TV) || (TV && !FV)) {
396 // Check that the simplified value has the form "X op Y" where "op" is the
397 // same as the original operation.
398 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
399 if (Simplified && Simplified->getOpcode() == Opcode) {
400 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
401 // We already know that "op" is the same as for the simplified value. See
402 // if the operands match too. If so, return the simplified value.
403 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
404 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
405 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
406 if (Simplified->getOperand(0) == UnsimplifiedLHS &&
407 Simplified->getOperand(1) == UnsimplifiedRHS)
409 if (Simplified->isCommutative() &&
410 Simplified->getOperand(1) == UnsimplifiedLHS &&
411 Simplified->getOperand(0) == UnsimplifiedRHS)
419 /// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
420 /// try to simplify the comparison by seeing whether both branches of the select
421 /// result in the same value. Returns the common value if so, otherwise returns
423 static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
424 Value *RHS, const Query &Q,
425 unsigned MaxRecurse) {
426 // Recursion is always used, so bail out at once if we already hit the limit.
430 // Make sure the select is on the LHS.
431 if (!isa<SelectInst>(LHS)) {
433 Pred = CmpInst::getSwappedPredicate(Pred);
435 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
436 SelectInst *SI = cast<SelectInst>(LHS);
437 Value *Cond = SI->getCondition();
438 Value *TV = SI->getTrueValue();
439 Value *FV = SI->getFalseValue();
441 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
442 // Does "cmp TV, RHS" simplify?
443 Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
445 // It not only simplified, it simplified to the select condition. Replace
447 TCmp = getTrue(Cond->getType());
449 // It didn't simplify. However if "cmp TV, RHS" is equal to the select
450 // condition then we can replace it with 'true'. Otherwise give up.
451 if (!isSameCompare(Cond, Pred, TV, RHS))
453 TCmp = getTrue(Cond->getType());
456 // Does "cmp FV, RHS" simplify?
457 Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
459 // It not only simplified, it simplified to the select condition. Replace
461 FCmp = getFalse(Cond->getType());
463 // It didn't simplify. However if "cmp FV, RHS" is equal to the select
464 // condition then we can replace it with 'false'. Otherwise give up.
465 if (!isSameCompare(Cond, Pred, FV, RHS))
467 FCmp = getFalse(Cond->getType());
470 // If both sides simplified to the same value, then use it as the result of
471 // the original comparison.
475 // The remaining cases only make sense if the select condition has the same
476 // type as the result of the comparison, so bail out if this is not so.
477 if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
479 // If the false value simplified to false, then the result of the compare
480 // is equal to "Cond && TCmp". This also catches the case when the false
481 // value simplified to false and the true value to true, returning "Cond".
482 if (match(FCmp, m_Zero()))
483 if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
485 // If the true value simplified to true, then the result of the compare
486 // is equal to "Cond || FCmp".
487 if (match(TCmp, m_One()))
488 if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
490 // Finally, if the false value simplified to true and the true value to
491 // false, then the result of the compare is equal to "!Cond".
492 if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
494 SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
501 /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
502 /// is a PHI instruction, try to simplify the binop by seeing whether evaluating
503 /// it on the incoming phi values yields the same result for every value. If so
504 /// returns the common value, otherwise returns null.
505 static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
506 const Query &Q, unsigned MaxRecurse) {
507 // Recursion is always used, so bail out at once if we already hit the limit.
512 if (isa<PHINode>(LHS)) {
513 PI = cast<PHINode>(LHS);
514 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
515 if (!ValueDominatesPHI(RHS, PI, Q.DT))
518 assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
519 PI = cast<PHINode>(RHS);
520 // Bail out if LHS and the phi may be mutually interdependent due to a loop.
521 if (!ValueDominatesPHI(LHS, PI, Q.DT))
525 // Evaluate the BinOp on the incoming phi values.
526 Value *CommonValue = 0;
527 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
528 Value *Incoming = PI->getIncomingValue(i);
529 // If the incoming value is the phi node itself, it can safely be skipped.
530 if (Incoming == PI) continue;
531 Value *V = PI == LHS ?
532 SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
533 SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
534 // If the operation failed to simplify, or simplified to a different value
535 // to previously, then give up.
536 if (!V || (CommonValue && V != CommonValue))
544 /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
545 /// try to simplify the comparison by seeing whether comparing with all of the
546 /// incoming phi values yields the same result every time. If so returns the
547 /// common result, otherwise returns null.
548 static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
549 const Query &Q, unsigned MaxRecurse) {
550 // Recursion is always used, so bail out at once if we already hit the limit.
554 // Make sure the phi is on the LHS.
555 if (!isa<PHINode>(LHS)) {
557 Pred = CmpInst::getSwappedPredicate(Pred);
559 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
560 PHINode *PI = cast<PHINode>(LHS);
562 // Bail out if RHS and the phi may be mutually interdependent due to a loop.
563 if (!ValueDominatesPHI(RHS, PI, Q.DT))
566 // Evaluate the BinOp on the incoming phi values.
567 Value *CommonValue = 0;
568 for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
569 Value *Incoming = PI->getIncomingValue(i);
570 // If the incoming value is the phi node itself, it can safely be skipped.
571 if (Incoming == PI) continue;
572 Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
573 // If the operation failed to simplify, or simplified to a different value
574 // to previously, then give up.
575 if (!V || (CommonValue && V != CommonValue))
583 /// SimplifyAddInst - Given operands for an Add, see if we can
584 /// fold the result. If not, this returns null.
585 static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
586 const Query &Q, unsigned MaxRecurse) {
587 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
588 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
589 Constant *Ops[] = { CLHS, CRHS };
590 return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops,
594 // Canonicalize the constant to the RHS.
598 // X + undef -> undef
599 if (match(Op1, m_Undef()))
603 if (match(Op1, m_Zero()))
610 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
611 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
614 // X + ~X -> -1 since ~X = -X-1
615 if (match(Op0, m_Not(m_Specific(Op1))) ||
616 match(Op1, m_Not(m_Specific(Op0))))
617 return Constant::getAllOnesValue(Op0->getType());
620 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
621 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
624 // Try some generic simplifications for associative operations.
625 if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
629 // Mul distributes over Add. Try some generic simplifications based on this.
630 if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
634 // Threading Add over selects and phi nodes is pointless, so don't bother.
635 // Threading over the select in "A + select(cond, B, C)" means evaluating
636 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
637 // only if B and C are equal. If B and C are equal then (since we assume
638 // that operands have already been simplified) "select(cond, B, C)" should
639 // have been simplified to the common value of B and C already. Analysing
640 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
641 // for threading over phi nodes.
646 Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
647 const TargetData *TD, const TargetLibraryInfo *TLI,
648 const DominatorTree *DT) {
649 return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
653 /// \brief Accumulate the constant integer offset a GEP represents.
655 /// Given a getelementptr instruction/constantexpr, accumulate the constant
656 /// offset from the base pointer into the provided APInt 'Offset'. Returns true
657 /// if the GEP has all-constant indices. Returns false if any non-constant
658 /// index is encountered leaving the 'Offset' in an undefined state. The
659 /// 'Offset' APInt must be the bitwidth of the target's pointer size.
660 static bool accumulateGEPOffset(const TargetData &TD, GEPOperator *GEP,
662 unsigned IntPtrWidth = TD.getPointerSizeInBits();
663 assert(IntPtrWidth == Offset.getBitWidth());
665 gep_type_iterator GTI = gep_type_begin(GEP);
666 for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E;
668 ConstantInt *OpC = dyn_cast<ConstantInt>(*I);
669 if (!OpC) return false;
670 if (OpC->isZero()) continue;
672 // Handle a struct index, which adds its field offset to the pointer.
673 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
674 unsigned ElementIdx = OpC->getZExtValue();
675 const StructLayout *SL = TD.getStructLayout(STy);
676 Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx),
681 APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType()),
683 Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
688 /// \brief Compute the base pointer and cumulative constant offsets for V.
690 /// This strips all constant offsets off of V, leaving it the base pointer, and
691 /// accumulates the total constant offset applied in the returned constant. It
692 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
693 /// no constant offsets applied.
694 static Constant *stripAndComputeConstantOffsets(const TargetData &TD,
696 if (!V->getType()->isPointerTy())
699 unsigned IntPtrWidth = TD.getPointerSizeInBits();
700 APInt Offset = APInt::getNullValue(IntPtrWidth);
702 // Even though we don't look through PHI nodes, we could be called on an
703 // instruction in an unreachable block, which may be on a cycle.
704 SmallPtrSet<Value *, 4> Visited;
707 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
708 if (!accumulateGEPOffset(TD, GEP, Offset))
710 V = GEP->getPointerOperand();
711 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
712 V = cast<Operator>(V)->getOperand(0);
713 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
714 if (GA->mayBeOverridden())
716 V = GA->getAliasee();
720 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
721 } while (Visited.insert(V));
723 Type *IntPtrTy = TD.getIntPtrType(V->getContext());
724 return ConstantInt::get(IntPtrTy, Offset);
727 /// \brief Compute the constant difference between two pointer values.
728 /// If the difference is not a constant, returns zero.
729 static Constant *computePointerDifference(const TargetData &TD,
730 Value *LHS, Value *RHS) {
731 Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
734 Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
738 // If LHS and RHS are not related via constant offsets to the same base
739 // value, there is nothing we can do here.
743 // Otherwise, the difference of LHS - RHS can be computed as:
745 // = (LHSOffset + Base) - (RHSOffset + Base)
746 // = LHSOffset - RHSOffset
747 return ConstantExpr::getSub(LHSOffset, RHSOffset);
750 /// SimplifySubInst - Given operands for a Sub, see if we can
751 /// fold the result. If not, this returns null.
752 static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
753 const Query &Q, unsigned MaxRecurse) {
754 if (Constant *CLHS = dyn_cast<Constant>(Op0))
755 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
756 Constant *Ops[] = { CLHS, CRHS };
757 return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
761 // X - undef -> undef
762 // undef - X -> undef
763 if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
764 return UndefValue::get(Op0->getType());
767 if (match(Op1, m_Zero()))
772 return Constant::getNullValue(Op0->getType());
777 if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
778 match(Op0, m_Shl(m_Specific(Op1), m_One())))
781 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
782 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
783 Value *Y = 0, *Z = Op1;
784 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
785 // See if "V === Y - Z" simplifies.
786 if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
787 // It does! Now see if "X + V" simplifies.
788 if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
789 // It does, we successfully reassociated!
793 // See if "V === X - Z" simplifies.
794 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
795 // It does! Now see if "Y + V" simplifies.
796 if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
797 // It does, we successfully reassociated!
803 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
804 // For example, X - (X + 1) -> -1
806 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
807 // See if "V === X - Y" simplifies.
808 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
809 // It does! Now see if "V - Z" simplifies.
810 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
811 // It does, we successfully reassociated!
815 // See if "V === X - Z" simplifies.
816 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
817 // It does! Now see if "V - Y" simplifies.
818 if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
819 // It does, we successfully reassociated!
825 // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
826 // For example, X - (X - Y) -> Y.
828 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
829 // See if "V === Z - X" simplifies.
830 if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
831 // It does! Now see if "V + Y" simplifies.
832 if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
833 // It does, we successfully reassociated!
838 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
839 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
840 match(Op1, m_Trunc(m_Value(Y))))
841 if (X->getType() == Y->getType())
842 // See if "V === X - Y" simplifies.
843 if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
844 // It does! Now see if "trunc V" simplifies.
845 if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
846 // It does, return the simplified "trunc V".
849 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
850 if (Q.TD && match(Op0, m_PtrToInt(m_Value(X))) &&
851 match(Op1, m_PtrToInt(m_Value(Y))))
852 if (Constant *Result = computePointerDifference(*Q.TD, X, Y))
853 return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
855 // Mul distributes over Sub. Try some generic simplifications based on this.
856 if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
861 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
862 if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
865 // Threading Sub over selects and phi nodes is pointless, so don't bother.
866 // Threading over the select in "A - select(cond, B, C)" means evaluating
867 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
868 // only if B and C are equal. If B and C are equal then (since we assume
869 // that operands have already been simplified) "select(cond, B, C)" should
870 // have been simplified to the common value of B and C already. Analysing
871 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
872 // for threading over phi nodes.
877 Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
878 const TargetData *TD, const TargetLibraryInfo *TLI,
879 const DominatorTree *DT) {
880 return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
884 /// SimplifyMulInst - Given operands for a Mul, see if we can
885 /// fold the result. If not, this returns null.
886 static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
887 unsigned MaxRecurse) {
888 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
889 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
890 Constant *Ops[] = { CLHS, CRHS };
891 return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
895 // Canonicalize the constant to the RHS.
900 if (match(Op1, m_Undef()))
901 return Constant::getNullValue(Op0->getType());
904 if (match(Op1, m_Zero()))
908 if (match(Op1, m_One()))
911 // (X / Y) * Y -> X if the division is exact.
913 if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
914 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
918 if (MaxRecurse && Op0->getType()->isIntegerTy(1))
919 if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
922 // Try some generic simplifications for associative operations.
923 if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
927 // Mul distributes over Add. Try some generic simplifications based on this.
928 if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
932 // If the operation is with the result of a select instruction, check whether
933 // operating on either branch of the select always yields the same value.
934 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
935 if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
939 // If the operation is with the result of a phi instruction, check whether
940 // operating on all incoming values of the phi always yields the same value.
941 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
942 if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
949 Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
950 const TargetLibraryInfo *TLI,
951 const DominatorTree *DT) {
952 return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
955 /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
956 /// fold the result. If not, this returns null.
957 static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
958 const Query &Q, unsigned MaxRecurse) {
959 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
960 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
961 Constant *Ops[] = { C0, C1 };
962 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
966 bool isSigned = Opcode == Instruction::SDiv;
968 // X / undef -> undef
969 if (match(Op1, m_Undef()))
973 if (match(Op0, m_Undef()))
974 return Constant::getNullValue(Op0->getType());
976 // 0 / X -> 0, we don't need to preserve faults!
977 if (match(Op0, m_Zero()))
981 if (match(Op1, m_One()))
984 if (Op0->getType()->isIntegerTy(1))
985 // It can't be division by zero, hence it must be division by one.
990 return ConstantInt::get(Op0->getType(), 1);
992 // (X * Y) / Y -> X if the multiplication does not overflow.
993 Value *X = 0, *Y = 0;
994 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
995 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
996 OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
997 // If the Mul knows it does not overflow, then we are good to go.
998 if ((isSigned && Mul->hasNoSignedWrap()) ||
999 (!isSigned && Mul->hasNoUnsignedWrap()))
1001 // If X has the form X = A / Y then X * Y cannot overflow.
1002 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
1003 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
1007 // (X rem Y) / Y -> 0
1008 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
1009 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
1010 return Constant::getNullValue(Op0->getType());
1012 // If the operation is with the result of a select instruction, check whether
1013 // operating on either branch of the select always yields the same value.
1014 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1015 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1018 // If the operation is with the result of a phi instruction, check whether
1019 // operating on all incoming values of the phi always yields the same value.
1020 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1021 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1027 /// SimplifySDivInst - Given operands for an SDiv, see if we can
1028 /// fold the result. If not, this returns null.
1029 static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
1030 unsigned MaxRecurse) {
1031 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
1037 Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1038 const TargetLibraryInfo *TLI,
1039 const DominatorTree *DT) {
1040 return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1043 /// SimplifyUDivInst - Given operands for a UDiv, see if we can
1044 /// fold the result. If not, this returns null.
1045 static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
1046 unsigned MaxRecurse) {
1047 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
1053 Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1054 const TargetLibraryInfo *TLI,
1055 const DominatorTree *DT) {
1056 return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1059 static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q,
1061 // undef / X -> undef (the undef could be a snan).
1062 if (match(Op0, m_Undef()))
1065 // X / undef -> undef
1066 if (match(Op1, m_Undef()))
1072 Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
1073 const TargetLibraryInfo *TLI,
1074 const DominatorTree *DT) {
1075 return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1078 /// SimplifyRem - Given operands for an SRem or URem, see if we can
1079 /// fold the result. If not, this returns null.
1080 static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
1081 const Query &Q, unsigned MaxRecurse) {
1082 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1083 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1084 Constant *Ops[] = { C0, C1 };
1085 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1089 // X % undef -> undef
1090 if (match(Op1, m_Undef()))
1094 if (match(Op0, m_Undef()))
1095 return Constant::getNullValue(Op0->getType());
1097 // 0 % X -> 0, we don't need to preserve faults!
1098 if (match(Op0, m_Zero()))
1101 // X % 0 -> undef, we don't need to preserve faults!
1102 if (match(Op1, m_Zero()))
1103 return UndefValue::get(Op0->getType());
1106 if (match(Op1, m_One()))
1107 return Constant::getNullValue(Op0->getType());
1109 if (Op0->getType()->isIntegerTy(1))
1110 // It can't be remainder by zero, hence it must be remainder by one.
1111 return Constant::getNullValue(Op0->getType());
1115 return Constant::getNullValue(Op0->getType());
1117 // If the operation is with the result of a select instruction, check whether
1118 // operating on either branch of the select always yields the same value.
1119 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1120 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1123 // If the operation is with the result of a phi instruction, check whether
1124 // operating on all incoming values of the phi always yields the same value.
1125 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1126 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1132 /// SimplifySRemInst - Given operands for an SRem, see if we can
1133 /// fold the result. If not, this returns null.
1134 static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
1135 unsigned MaxRecurse) {
1136 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
1142 Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1143 const TargetLibraryInfo *TLI,
1144 const DominatorTree *DT) {
1145 return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1148 /// SimplifyURemInst - Given operands for a URem, see if we can
1149 /// fold the result. If not, this returns null.
1150 static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
1151 unsigned MaxRecurse) {
1152 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
1158 Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
1159 const TargetLibraryInfo *TLI,
1160 const DominatorTree *DT) {
1161 return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1164 static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &,
1166 // undef % X -> undef (the undef could be a snan).
1167 if (match(Op0, m_Undef()))
1170 // X % undef -> undef
1171 if (match(Op1, m_Undef()))
1177 Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD,
1178 const TargetLibraryInfo *TLI,
1179 const DominatorTree *DT) {
1180 return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1183 /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
1184 /// fold the result. If not, this returns null.
1185 static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
1186 const Query &Q, unsigned MaxRecurse) {
1187 if (Constant *C0 = dyn_cast<Constant>(Op0)) {
1188 if (Constant *C1 = dyn_cast<Constant>(Op1)) {
1189 Constant *Ops[] = { C0, C1 };
1190 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI);
1194 // 0 shift by X -> 0
1195 if (match(Op0, m_Zero()))
1198 // X shift by 0 -> X
1199 if (match(Op1, m_Zero()))
1202 // X shift by undef -> undef because it may shift by the bitwidth.
1203 if (match(Op1, m_Undef()))
1206 // Shifting by the bitwidth or more is undefined.
1207 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
1208 if (CI->getValue().getLimitedValue() >=
1209 Op0->getType()->getScalarSizeInBits())
1210 return UndefValue::get(Op0->getType());
1212 // If the operation is with the result of a select instruction, check whether
1213 // operating on either branch of the select always yields the same value.
1214 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1215 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
1218 // If the operation is with the result of a phi instruction, check whether
1219 // operating on all incoming values of the phi always yields the same value.
1220 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1221 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
1227 /// SimplifyShlInst - Given operands for an Shl, see if we can
1228 /// fold the result. If not, this returns null.
1229 static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1230 const Query &Q, unsigned MaxRecurse) {
1231 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
1235 if (match(Op0, m_Undef()))
1236 return Constant::getNullValue(Op0->getType());
1238 // (X >> A) << A -> X
1240 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
1245 Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
1246 const TargetData *TD, const TargetLibraryInfo *TLI,
1247 const DominatorTree *DT) {
1248 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT),
1252 /// SimplifyLShrInst - Given operands for an LShr, see if we can
1253 /// fold the result. If not, this returns null.
1254 static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1255 const Query &Q, unsigned MaxRecurse) {
1256 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse))
1260 if (match(Op0, m_Undef()))
1261 return Constant::getNullValue(Op0->getType());
1263 // (X << A) >> A -> X
1265 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1266 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
1272 Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
1273 const TargetData *TD,
1274 const TargetLibraryInfo *TLI,
1275 const DominatorTree *DT) {
1276 return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1280 /// SimplifyAShrInst - Given operands for an AShr, see if we can
1281 /// fold the result. If not, this returns null.
1282 static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1283 const Query &Q, unsigned MaxRecurse) {
1284 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse))
1287 // all ones >>a X -> all ones
1288 if (match(Op0, m_AllOnes()))
1291 // undef >>a X -> all ones
1292 if (match(Op0, m_Undef()))
1293 return Constant::getAllOnesValue(Op0->getType());
1295 // (X << A) >> A -> X
1297 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
1298 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
1304 Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
1305 const TargetData *TD,
1306 const TargetLibraryInfo *TLI,
1307 const DominatorTree *DT) {
1308 return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT),
1312 /// SimplifyAndInst - Given operands for an And, see if we can
1313 /// fold the result. If not, this returns null.
1314 static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
1315 unsigned MaxRecurse) {
1316 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1317 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1318 Constant *Ops[] = { CLHS, CRHS };
1319 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
1323 // Canonicalize the constant to the RHS.
1324 std::swap(Op0, Op1);
1328 if (match(Op1, m_Undef()))
1329 return Constant::getNullValue(Op0->getType());
1336 if (match(Op1, m_Zero()))
1340 if (match(Op1, m_AllOnes()))
1343 // A & ~A = ~A & A = 0
1344 if (match(Op0, m_Not(m_Specific(Op1))) ||
1345 match(Op1, m_Not(m_Specific(Op0))))
1346 return Constant::getNullValue(Op0->getType());
1349 Value *A = 0, *B = 0;
1350 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1351 (A == Op1 || B == Op1))
1355 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1356 (A == Op0 || B == Op0))
1359 // A & (-A) = A if A is a power of two or zero.
1360 if (match(Op0, m_Neg(m_Specific(Op1))) ||
1361 match(Op1, m_Neg(m_Specific(Op0)))) {
1362 if (isPowerOfTwo(Op0, Q.TD, /*OrZero*/true))
1364 if (isPowerOfTwo(Op1, Q.TD, /*OrZero*/true))
1368 // Try some generic simplifications for associative operations.
1369 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
1373 // And distributes over Or. Try some generic simplifications based on this.
1374 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1378 // And distributes over Xor. Try some generic simplifications based on this.
1379 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
1383 // Or distributes over And. Try some generic simplifications based on this.
1384 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
1388 // If the operation is with the result of a select instruction, check whether
1389 // operating on either branch of the select always yields the same value.
1390 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1391 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
1395 // If the operation is with the result of a phi instruction, check whether
1396 // operating on all incoming values of the phi always yields the same value.
1397 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1398 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
1405 Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
1406 const TargetLibraryInfo *TLI,
1407 const DominatorTree *DT) {
1408 return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1411 /// SimplifyOrInst - Given operands for an Or, see if we can
1412 /// fold the result. If not, this returns null.
1413 static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
1414 unsigned MaxRecurse) {
1415 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1416 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1417 Constant *Ops[] = { CLHS, CRHS };
1418 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
1422 // Canonicalize the constant to the RHS.
1423 std::swap(Op0, Op1);
1427 if (match(Op1, m_Undef()))
1428 return Constant::getAllOnesValue(Op0->getType());
1435 if (match(Op1, m_Zero()))
1439 if (match(Op1, m_AllOnes()))
1442 // A | ~A = ~A | A = -1
1443 if (match(Op0, m_Not(m_Specific(Op1))) ||
1444 match(Op1, m_Not(m_Specific(Op0))))
1445 return Constant::getAllOnesValue(Op0->getType());
1448 Value *A = 0, *B = 0;
1449 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1450 (A == Op1 || B == Op1))
1454 if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
1455 (A == Op0 || B == Op0))
1458 // ~(A & ?) | A = -1
1459 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1460 (A == Op1 || B == Op1))
1461 return Constant::getAllOnesValue(Op1->getType());
1463 // A | ~(A & ?) = -1
1464 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
1465 (A == Op0 || B == Op0))
1466 return Constant::getAllOnesValue(Op0->getType());
1468 // Try some generic simplifications for associative operations.
1469 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
1473 // Or distributes over And. Try some generic simplifications based on this.
1474 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
1478 // And distributes over Or. Try some generic simplifications based on this.
1479 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
1483 // If the operation is with the result of a select instruction, check whether
1484 // operating on either branch of the select always yields the same value.
1485 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
1486 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
1490 // If the operation is with the result of a phi instruction, check whether
1491 // operating on all incoming values of the phi always yields the same value.
1492 if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
1493 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
1499 Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
1500 const TargetLibraryInfo *TLI,
1501 const DominatorTree *DT) {
1502 return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1505 /// SimplifyXorInst - Given operands for a Xor, see if we can
1506 /// fold the result. If not, this returns null.
1507 static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
1508 unsigned MaxRecurse) {
1509 if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
1510 if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
1511 Constant *Ops[] = { CLHS, CRHS };
1512 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
1516 // Canonicalize the constant to the RHS.
1517 std::swap(Op0, Op1);
1520 // A ^ undef -> undef
1521 if (match(Op1, m_Undef()))
1525 if (match(Op1, m_Zero()))
1530 return Constant::getNullValue(Op0->getType());
1532 // A ^ ~A = ~A ^ A = -1
1533 if (match(Op0, m_Not(m_Specific(Op1))) ||
1534 match(Op1, m_Not(m_Specific(Op0))))
1535 return Constant::getAllOnesValue(Op0->getType());
1537 // Try some generic simplifications for associative operations.
1538 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
1542 // And distributes over Xor. Try some generic simplifications based on this.
1543 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
1547 // Threading Xor over selects and phi nodes is pointless, so don't bother.
1548 // Threading over the select in "A ^ select(cond, B, C)" means evaluating
1549 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
1550 // only if B and C are equal. If B and C are equal then (since we assume
1551 // that operands have already been simplified) "select(cond, B, C)" should
1552 // have been simplified to the common value of B and C already. Analysing
1553 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
1554 // for threading over phi nodes.
1559 Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
1560 const TargetLibraryInfo *TLI,
1561 const DominatorTree *DT) {
1562 return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit);
1565 static Type *GetCompareTy(Value *Op) {
1566 return CmpInst::makeCmpResultType(Op->getType());
1569 /// ExtractEquivalentCondition - Rummage around inside V looking for something
1570 /// equivalent to the comparison "LHS Pred RHS". Return such a value if found,
1571 /// otherwise return null. Helper function for analyzing max/min idioms.
1572 static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
1573 Value *LHS, Value *RHS) {
1574 SelectInst *SI = dyn_cast<SelectInst>(V);
1577 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
1580 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
1581 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
1583 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
1584 LHS == CmpRHS && RHS == CmpLHS)
1590 /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
1591 /// fold the result. If not, this returns null.
1592 static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
1593 const Query &Q, unsigned MaxRecurse) {
1594 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
1595 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
1597 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
1598 if (Constant *CRHS = dyn_cast<Constant>(RHS))
1599 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
1601 // If we have a constant, make sure it is on the RHS.
1602 std::swap(LHS, RHS);
1603 Pred = CmpInst::getSwappedPredicate(Pred);
1606 Type *ITy = GetCompareTy(LHS); // The return type.
1607 Type *OpTy = LHS->getType(); // The operand type.
1609 // icmp X, X -> true/false
1610 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
1611 // because X could be 0.
1612 if (LHS == RHS || isa<UndefValue>(RHS))
1613 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1615 // Special case logic when the operands have i1 type.
1616 if (OpTy->getScalarType()->isIntegerTy(1)) {
1619 case ICmpInst::ICMP_EQ:
1621 if (match(RHS, m_One()))
1624 case ICmpInst::ICMP_NE:
1626 if (match(RHS, m_Zero()))
1629 case ICmpInst::ICMP_UGT:
1631 if (match(RHS, m_Zero()))
1634 case ICmpInst::ICMP_UGE:
1636 if (match(RHS, m_One()))
1639 case ICmpInst::ICMP_SLT:
1641 if (match(RHS, m_Zero()))
1644 case ICmpInst::ICMP_SLE:
1646 if (match(RHS, m_One()))
1652 // icmp <object*>, <object*/null> - Different identified objects have
1653 // different addresses (unless null), and what's more the address of an
1654 // identified local is never equal to another argument (again, barring null).
1655 // Note that generalizing to the case where LHS is a global variable address
1656 // or null is pointless, since if both LHS and RHS are constants then we
1657 // already constant folded the compare, and if only one of them is then we
1658 // moved it to RHS already.
1659 Value *LHSPtr = LHS->stripPointerCasts();
1660 Value *RHSPtr = RHS->stripPointerCasts();
1661 if (LHSPtr == RHSPtr)
1662 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
1664 // Be more aggressive about stripping pointer adjustments when checking a
1665 // comparison of an alloca address to another object. We can rip off all
1666 // inbounds GEP operations, even if they are variable.
1667 LHSPtr = LHSPtr->stripInBoundsOffsets();
1668 if (llvm::isIdentifiedObject(LHSPtr)) {
1669 RHSPtr = RHSPtr->stripInBoundsOffsets();
1670 if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) {
1671 // If both sides are different identified objects, they aren't equal
1672 // unless they're null.
1673 if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) &&
1674 Pred == CmpInst::ICMP_EQ)
1675 return ConstantInt::get(ITy, false);
1677 // A local identified object (alloca or noalias call) can't equal any
1678 // incoming argument, unless they're both null.
1679 if (isa<Instruction>(LHSPtr) && isa<Argument>(RHSPtr) &&
1680 Pred == CmpInst::ICMP_EQ)
1681 return ConstantInt::get(ITy, false);
1684 // Assume that the constant null is on the right.
1685 if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) {
1686 if (Pred == CmpInst::ICMP_EQ)
1687 return ConstantInt::get(ITy, false);
1688 else if (Pred == CmpInst::ICMP_NE)
1689 return ConstantInt::get(ITy, true);
1691 } else if (isa<Argument>(LHSPtr)) {
1692 RHSPtr = RHSPtr->stripInBoundsOffsets();
1693 // An alloca can't be equal to an argument.
1694 if (isa<AllocaInst>(RHSPtr)) {
1695 if (Pred == CmpInst::ICMP_EQ)
1696 return ConstantInt::get(ITy, false);
1697 else if (Pred == CmpInst::ICMP_NE)
1698 return ConstantInt::get(ITy, true);
1702 // If we are comparing with zero then try hard since this is a common case.
1703 if (match(RHS, m_Zero())) {
1704 bool LHSKnownNonNegative, LHSKnownNegative;
1706 default: llvm_unreachable("Unknown ICmp predicate!");
1707 case ICmpInst::ICMP_ULT:
1708 return getFalse(ITy);
1709 case ICmpInst::ICMP_UGE:
1710 return getTrue(ITy);
1711 case ICmpInst::ICMP_EQ:
1712 case ICmpInst::ICMP_ULE:
1713 if (isKnownNonZero(LHS, Q.TD))
1714 return getFalse(ITy);
1716 case ICmpInst::ICMP_NE:
1717 case ICmpInst::ICMP_UGT:
1718 if (isKnownNonZero(LHS, Q.TD))
1719 return getTrue(ITy);
1721 case ICmpInst::ICMP_SLT:
1722 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1723 if (LHSKnownNegative)
1724 return getTrue(ITy);
1725 if (LHSKnownNonNegative)
1726 return getFalse(ITy);
1728 case ICmpInst::ICMP_SLE:
1729 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1730 if (LHSKnownNegative)
1731 return getTrue(ITy);
1732 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1733 return getFalse(ITy);
1735 case ICmpInst::ICMP_SGE:
1736 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1737 if (LHSKnownNegative)
1738 return getFalse(ITy);
1739 if (LHSKnownNonNegative)
1740 return getTrue(ITy);
1742 case ICmpInst::ICMP_SGT:
1743 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD);
1744 if (LHSKnownNegative)
1745 return getFalse(ITy);
1746 if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD))
1747 return getTrue(ITy);
1752 // See if we are doing a comparison with a constant integer.
1753 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1754 // Rule out tautological comparisons (eg., ult 0 or uge 0).
1755 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
1756 if (RHS_CR.isEmptySet())
1757 return ConstantInt::getFalse(CI->getContext());
1758 if (RHS_CR.isFullSet())
1759 return ConstantInt::getTrue(CI->getContext());
1761 // Many binary operators with constant RHS have easy to compute constant
1762 // range. Use them to check whether the comparison is a tautology.
1763 uint32_t Width = CI->getBitWidth();
1764 APInt Lower = APInt(Width, 0);
1765 APInt Upper = APInt(Width, 0);
1767 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
1768 // 'urem x, CI2' produces [0, CI2).
1769 Upper = CI2->getValue();
1770 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
1771 // 'srem x, CI2' produces (-|CI2|, |CI2|).
1772 Upper = CI2->getValue().abs();
1773 Lower = (-Upper) + 1;
1774 } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
1775 // 'udiv CI2, x' produces [0, CI2].
1776 Upper = CI2->getValue() + 1;
1777 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
1778 // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
1779 APInt NegOne = APInt::getAllOnesValue(Width);
1781 Upper = NegOne.udiv(CI2->getValue()) + 1;
1782 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
1783 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
1784 APInt IntMin = APInt::getSignedMinValue(Width);
1785 APInt IntMax = APInt::getSignedMaxValue(Width);
1786 APInt Val = CI2->getValue().abs();
1787 if (!Val.isMinValue()) {
1788 Lower = IntMin.sdiv(Val);
1789 Upper = IntMax.sdiv(Val) + 1;
1791 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
1792 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
1793 APInt NegOne = APInt::getAllOnesValue(Width);
1794 if (CI2->getValue().ult(Width))
1795 Upper = NegOne.lshr(CI2->getValue()) + 1;
1796 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
1797 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
1798 APInt IntMin = APInt::getSignedMinValue(Width);
1799 APInt IntMax = APInt::getSignedMaxValue(Width);
1800 if (CI2->getValue().ult(Width)) {
1801 Lower = IntMin.ashr(CI2->getValue());
1802 Upper = IntMax.ashr(CI2->getValue()) + 1;
1804 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
1805 // 'or x, CI2' produces [CI2, UINT_MAX].
1806 Lower = CI2->getValue();
1807 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
1808 // 'and x, CI2' produces [0, CI2].
1809 Upper = CI2->getValue() + 1;
1811 if (Lower != Upper) {
1812 ConstantRange LHS_CR = ConstantRange(Lower, Upper);
1813 if (RHS_CR.contains(LHS_CR))
1814 return ConstantInt::getTrue(RHS->getContext());
1815 if (RHS_CR.inverse().contains(LHS_CR))
1816 return ConstantInt::getFalse(RHS->getContext());
1820 // Compare of cast, for example (zext X) != 0 -> X != 0
1821 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
1822 Instruction *LI = cast<CastInst>(LHS);
1823 Value *SrcOp = LI->getOperand(0);
1824 Type *SrcTy = SrcOp->getType();
1825 Type *DstTy = LI->getType();
1827 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
1828 // if the integer type is the same size as the pointer type.
1829 if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) &&
1830 Q.TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
1831 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
1832 // Transfer the cast to the constant.
1833 if (Value *V = SimplifyICmpInst(Pred, SrcOp,
1834 ConstantExpr::getIntToPtr(RHSC, SrcTy),
1837 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
1838 if (RI->getOperand(0)->getType() == SrcTy)
1839 // Compare without the cast.
1840 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1846 if (isa<ZExtInst>(LHS)) {
1847 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
1849 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
1850 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1851 // Compare X and Y. Note that signed predicates become unsigned.
1852 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1853 SrcOp, RI->getOperand(0), Q,
1857 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
1858 // too. If not, then try to deduce the result of the comparison.
1859 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1860 // Compute the constant that would happen if we truncated to SrcTy then
1861 // reextended to DstTy.
1862 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1863 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
1865 // If the re-extended constant didn't change then this is effectively
1866 // also a case of comparing two zero-extended values.
1867 if (RExt == CI && MaxRecurse)
1868 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
1869 SrcOp, Trunc, Q, MaxRecurse-1))
1872 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
1873 // there. Use this to work out the result of the comparison.
1876 default: llvm_unreachable("Unknown ICmp predicate!");
1878 case ICmpInst::ICMP_EQ:
1879 case ICmpInst::ICMP_UGT:
1880 case ICmpInst::ICMP_UGE:
1881 return ConstantInt::getFalse(CI->getContext());
1883 case ICmpInst::ICMP_NE:
1884 case ICmpInst::ICMP_ULT:
1885 case ICmpInst::ICMP_ULE:
1886 return ConstantInt::getTrue(CI->getContext());
1888 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
1889 // is non-negative then LHS <s RHS.
1890 case ICmpInst::ICMP_SGT:
1891 case ICmpInst::ICMP_SGE:
1892 return CI->getValue().isNegative() ?
1893 ConstantInt::getTrue(CI->getContext()) :
1894 ConstantInt::getFalse(CI->getContext());
1896 case ICmpInst::ICMP_SLT:
1897 case ICmpInst::ICMP_SLE:
1898 return CI->getValue().isNegative() ?
1899 ConstantInt::getFalse(CI->getContext()) :
1900 ConstantInt::getTrue(CI->getContext());
1906 if (isa<SExtInst>(LHS)) {
1907 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
1909 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
1910 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
1911 // Compare X and Y. Note that the predicate does not change.
1912 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
1916 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
1917 // too. If not, then try to deduce the result of the comparison.
1918 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1919 // Compute the constant that would happen if we truncated to SrcTy then
1920 // reextended to DstTy.
1921 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
1922 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
1924 // If the re-extended constant didn't change then this is effectively
1925 // also a case of comparing two sign-extended values.
1926 if (RExt == CI && MaxRecurse)
1927 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
1930 // Otherwise the upper bits of LHS are all equal, while RHS has varying
1931 // bits there. Use this to work out the result of the comparison.
1934 default: llvm_unreachable("Unknown ICmp predicate!");
1935 case ICmpInst::ICMP_EQ:
1936 return ConstantInt::getFalse(CI->getContext());
1937 case ICmpInst::ICMP_NE:
1938 return ConstantInt::getTrue(CI->getContext());
1940 // If RHS is non-negative then LHS <s RHS. If RHS is negative then
1942 case ICmpInst::ICMP_SGT:
1943 case ICmpInst::ICMP_SGE:
1944 return CI->getValue().isNegative() ?
1945 ConstantInt::getTrue(CI->getContext()) :
1946 ConstantInt::getFalse(CI->getContext());
1947 case ICmpInst::ICMP_SLT:
1948 case ICmpInst::ICMP_SLE:
1949 return CI->getValue().isNegative() ?
1950 ConstantInt::getFalse(CI->getContext()) :
1951 ConstantInt::getTrue(CI->getContext());
1953 // If LHS is non-negative then LHS <u RHS. If LHS is negative then
1955 case ICmpInst::ICMP_UGT:
1956 case ICmpInst::ICMP_UGE:
1957 // Comparison is true iff the LHS <s 0.
1959 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
1960 Constant::getNullValue(SrcTy),
1964 case ICmpInst::ICMP_ULT:
1965 case ICmpInst::ICMP_ULE:
1966 // Comparison is true iff the LHS >=s 0.
1968 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
1969 Constant::getNullValue(SrcTy),
1979 // Special logic for binary operators.
1980 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
1981 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
1982 if (MaxRecurse && (LBO || RBO)) {
1983 // Analyze the case when either LHS or RHS is an add instruction.
1984 Value *A = 0, *B = 0, *C = 0, *D = 0;
1985 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
1986 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
1987 if (LBO && LBO->getOpcode() == Instruction::Add) {
1988 A = LBO->getOperand(0); B = LBO->getOperand(1);
1989 NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
1990 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
1991 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
1993 if (RBO && RBO->getOpcode() == Instruction::Add) {
1994 C = RBO->getOperand(0); D = RBO->getOperand(1);
1995 NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
1996 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
1997 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
2000 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2001 if ((A == RHS || B == RHS) && NoLHSWrapProblem)
2002 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
2003 Constant::getNullValue(RHS->getType()),
2007 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2008 if ((C == LHS || D == LHS) && NoRHSWrapProblem)
2009 if (Value *V = SimplifyICmpInst(Pred,
2010 Constant::getNullValue(LHS->getType()),
2011 C == LHS ? D : C, Q, MaxRecurse-1))
2014 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
2015 if (A && C && (A == C || A == D || B == C || B == D) &&
2016 NoLHSWrapProblem && NoRHSWrapProblem) {
2017 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2018 Value *Y = (A == C || A == D) ? B : A;
2019 Value *Z = (C == A || C == B) ? D : C;
2020 if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
2025 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
2026 bool KnownNonNegative, KnownNegative;
2030 case ICmpInst::ICMP_SGT:
2031 case ICmpInst::ICMP_SGE:
2032 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2033 if (!KnownNonNegative)
2036 case ICmpInst::ICMP_EQ:
2037 case ICmpInst::ICMP_UGT:
2038 case ICmpInst::ICMP_UGE:
2039 return getFalse(ITy);
2040 case ICmpInst::ICMP_SLT:
2041 case ICmpInst::ICMP_SLE:
2042 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD);
2043 if (!KnownNonNegative)
2046 case ICmpInst::ICMP_NE:
2047 case ICmpInst::ICMP_ULT:
2048 case ICmpInst::ICMP_ULE:
2049 return getTrue(ITy);
2052 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
2053 bool KnownNonNegative, KnownNegative;
2057 case ICmpInst::ICMP_SGT:
2058 case ICmpInst::ICMP_SGE:
2059 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2060 if (!KnownNonNegative)
2063 case ICmpInst::ICMP_NE:
2064 case ICmpInst::ICMP_UGT:
2065 case ICmpInst::ICMP_UGE:
2066 return getTrue(ITy);
2067 case ICmpInst::ICMP_SLT:
2068 case ICmpInst::ICMP_SLE:
2069 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD);
2070 if (!KnownNonNegative)
2073 case ICmpInst::ICMP_EQ:
2074 case ICmpInst::ICMP_ULT:
2075 case ICmpInst::ICMP_ULE:
2076 return getFalse(ITy);
2081 if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
2082 // icmp pred (X /u Y), X
2083 if (Pred == ICmpInst::ICMP_UGT)
2084 return getFalse(ITy);
2085 if (Pred == ICmpInst::ICMP_ULE)
2086 return getTrue(ITy);
2089 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
2090 LBO->getOperand(1) == RBO->getOperand(1)) {
2091 switch (LBO->getOpcode()) {
2093 case Instruction::UDiv:
2094 case Instruction::LShr:
2095 if (ICmpInst::isSigned(Pred))
2098 case Instruction::SDiv:
2099 case Instruction::AShr:
2100 if (!LBO->isExact() || !RBO->isExact())
2102 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2103 RBO->getOperand(0), Q, MaxRecurse-1))
2106 case Instruction::Shl: {
2107 bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
2108 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
2111 if (!NSW && ICmpInst::isSigned(Pred))
2113 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
2114 RBO->getOperand(0), Q, MaxRecurse-1))
2121 // Simplify comparisons involving max/min.
2123 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
2124 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
2126 // Signed variants on "max(a,b)>=a -> true".
2127 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2128 if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
2129 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2130 // We analyze this as smax(A, B) pred A.
2132 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
2133 (A == LHS || B == LHS)) {
2134 if (A != LHS) std::swap(A, B); // A pred smax(A, B).
2135 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
2136 // We analyze this as smax(A, B) swapped-pred A.
2137 P = CmpInst::getSwappedPredicate(Pred);
2138 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2139 (A == RHS || B == RHS)) {
2140 if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
2141 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2142 // We analyze this as smax(-A, -B) swapped-pred -A.
2143 // Note that we do not need to actually form -A or -B thanks to EqP.
2144 P = CmpInst::getSwappedPredicate(Pred);
2145 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
2146 (A == LHS || B == LHS)) {
2147 if (A != LHS) std::swap(A, B); // A pred smin(A, B).
2148 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
2149 // We analyze this as smax(-A, -B) pred -A.
2150 // Note that we do not need to actually form -A or -B thanks to EqP.
2153 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2154 // Cases correspond to "max(A, B) p A".
2158 case CmpInst::ICMP_EQ:
2159 case CmpInst::ICMP_SLE:
2160 // Equivalent to "A EqP B". This may be the same as the condition tested
2161 // in the max/min; if so, we can just return that.
2162 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2164 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2166 // Otherwise, see if "A EqP B" simplifies.
2168 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2171 case CmpInst::ICMP_NE:
2172 case CmpInst::ICMP_SGT: {
2173 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2174 // Equivalent to "A InvEqP B". This may be the same as the condition
2175 // tested in the max/min; if so, we can just return that.
2176 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2178 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2180 // Otherwise, see if "A InvEqP B" simplifies.
2182 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2186 case CmpInst::ICMP_SGE:
2188 return getTrue(ITy);
2189 case CmpInst::ICMP_SLT:
2191 return getFalse(ITy);
2195 // Unsigned variants on "max(a,b)>=a -> true".
2196 P = CmpInst::BAD_ICMP_PREDICATE;
2197 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
2198 if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
2199 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2200 // We analyze this as umax(A, B) pred A.
2202 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
2203 (A == LHS || B == LHS)) {
2204 if (A != LHS) std::swap(A, B); // A pred umax(A, B).
2205 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
2206 // We analyze this as umax(A, B) swapped-pred A.
2207 P = CmpInst::getSwappedPredicate(Pred);
2208 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2209 (A == RHS || B == RHS)) {
2210 if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
2211 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2212 // We analyze this as umax(-A, -B) swapped-pred -A.
2213 // Note that we do not need to actually form -A or -B thanks to EqP.
2214 P = CmpInst::getSwappedPredicate(Pred);
2215 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
2216 (A == LHS || B == LHS)) {
2217 if (A != LHS) std::swap(A, B); // A pred umin(A, B).
2218 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
2219 // We analyze this as umax(-A, -B) pred -A.
2220 // Note that we do not need to actually form -A or -B thanks to EqP.
2223 if (P != CmpInst::BAD_ICMP_PREDICATE) {
2224 // Cases correspond to "max(A, B) p A".
2228 case CmpInst::ICMP_EQ:
2229 case CmpInst::ICMP_ULE:
2230 // Equivalent to "A EqP B". This may be the same as the condition tested
2231 // in the max/min; if so, we can just return that.
2232 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
2234 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
2236 // Otherwise, see if "A EqP B" simplifies.
2238 if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
2241 case CmpInst::ICMP_NE:
2242 case CmpInst::ICMP_UGT: {
2243 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
2244 // Equivalent to "A InvEqP B". This may be the same as the condition
2245 // tested in the max/min; if so, we can just return that.
2246 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
2248 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
2250 // Otherwise, see if "A InvEqP B" simplifies.
2252 if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
2256 case CmpInst::ICMP_UGE:
2258 return getTrue(ITy);
2259 case CmpInst::ICMP_ULT:
2261 return getFalse(ITy);
2265 // Variants on "max(x,y) >= min(x,z)".
2267 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
2268 match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
2269 (A == C || A == D || B == C || B == D)) {
2270 // max(x, ?) pred min(x, ?).
2271 if (Pred == CmpInst::ICMP_SGE)
2273 return getTrue(ITy);
2274 if (Pred == CmpInst::ICMP_SLT)
2276 return getFalse(ITy);
2277 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
2278 match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
2279 (A == C || A == D || B == C || B == D)) {
2280 // min(x, ?) pred max(x, ?).
2281 if (Pred == CmpInst::ICMP_SLE)
2283 return getTrue(ITy);
2284 if (Pred == CmpInst::ICMP_SGT)
2286 return getFalse(ITy);
2287 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
2288 match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
2289 (A == C || A == D || B == C || B == D)) {
2290 // max(x, ?) pred min(x, ?).
2291 if (Pred == CmpInst::ICMP_UGE)
2293 return getTrue(ITy);
2294 if (Pred == CmpInst::ICMP_ULT)
2296 return getFalse(ITy);
2297 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
2298 match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
2299 (A == C || A == D || B == C || B == D)) {
2300 // min(x, ?) pred max(x, ?).
2301 if (Pred == CmpInst::ICMP_ULE)
2303 return getTrue(ITy);
2304 if (Pred == CmpInst::ICMP_UGT)
2306 return getFalse(ITy);
2309 // Simplify comparisons of GEPs.
2310 if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
2311 if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
2312 if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
2313 GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
2314 (ICmpInst::isEquality(Pred) ||
2315 (GLHS->isInBounds() && GRHS->isInBounds() &&
2316 Pred == ICmpInst::getSignedPredicate(Pred)))) {
2317 // The bases are equal and the indices are constant. Build a constant
2318 // expression GEP with the same indices and a null base pointer to see
2319 // what constant folding can make out of it.
2320 Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
2321 SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
2322 Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS);
2324 SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
2325 Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS);
2326 return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
2331 // If the comparison is with the result of a select instruction, check whether
2332 // comparing with either branch of the select always yields the same value.
2333 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2334 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2337 // If the comparison is with the result of a phi instruction, check whether
2338 // doing the compare with each incoming phi value yields a common result.
2339 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2340 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2346 Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2347 const TargetData *TD,
2348 const TargetLibraryInfo *TLI,
2349 const DominatorTree *DT) {
2350 return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2354 /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
2355 /// fold the result. If not, this returns null.
2356 static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2357 const Query &Q, unsigned MaxRecurse) {
2358 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
2359 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
2361 if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
2362 if (Constant *CRHS = dyn_cast<Constant>(RHS))
2363 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI);
2365 // If we have a constant, make sure it is on the RHS.
2366 std::swap(LHS, RHS);
2367 Pred = CmpInst::getSwappedPredicate(Pred);
2370 // Fold trivial predicates.
2371 if (Pred == FCmpInst::FCMP_FALSE)
2372 return ConstantInt::get(GetCompareTy(LHS), 0);
2373 if (Pred == FCmpInst::FCMP_TRUE)
2374 return ConstantInt::get(GetCompareTy(LHS), 1);
2376 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
2377 return UndefValue::get(GetCompareTy(LHS));
2379 // fcmp x,x -> true/false. Not all compares are foldable.
2381 if (CmpInst::isTrueWhenEqual(Pred))
2382 return ConstantInt::get(GetCompareTy(LHS), 1);
2383 if (CmpInst::isFalseWhenEqual(Pred))
2384 return ConstantInt::get(GetCompareTy(LHS), 0);
2387 // Handle fcmp with constant RHS
2388 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2389 // If the constant is a nan, see if we can fold the comparison based on it.
2390 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2391 if (CFP->getValueAPF().isNaN()) {
2392 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
2393 return ConstantInt::getFalse(CFP->getContext());
2394 assert(FCmpInst::isUnordered(Pred) &&
2395 "Comparison must be either ordered or unordered!");
2396 // True if unordered.
2397 return ConstantInt::getTrue(CFP->getContext());
2399 // Check whether the constant is an infinity.
2400 if (CFP->getValueAPF().isInfinity()) {
2401 if (CFP->getValueAPF().isNegative()) {
2403 case FCmpInst::FCMP_OLT:
2404 // No value is ordered and less than negative infinity.
2405 return ConstantInt::getFalse(CFP->getContext());
2406 case FCmpInst::FCMP_UGE:
2407 // All values are unordered with or at least negative infinity.
2408 return ConstantInt::getTrue(CFP->getContext());
2414 case FCmpInst::FCMP_OGT:
2415 // No value is ordered and greater than infinity.
2416 return ConstantInt::getFalse(CFP->getContext());
2417 case FCmpInst::FCMP_ULE:
2418 // All values are unordered with and at most infinity.
2419 return ConstantInt::getTrue(CFP->getContext());
2428 // If the comparison is with the result of a select instruction, check whether
2429 // comparing with either branch of the select always yields the same value.
2430 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2431 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
2434 // If the comparison is with the result of a phi instruction, check whether
2435 // doing the compare with each incoming phi value yields a common result.
2436 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2437 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
2443 Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2444 const TargetData *TD,
2445 const TargetLibraryInfo *TLI,
2446 const DominatorTree *DT) {
2447 return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2451 /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
2452 /// the result. If not, this returns null.
2453 static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
2454 Value *FalseVal, const Query &Q,
2455 unsigned MaxRecurse) {
2456 // select true, X, Y -> X
2457 // select false, X, Y -> Y
2458 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
2459 return CB->getZExtValue() ? TrueVal : FalseVal;
2461 // select C, X, X -> X
2462 if (TrueVal == FalseVal)
2465 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2466 if (isa<Constant>(TrueVal))
2470 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2472 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2478 Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
2479 const TargetData *TD,
2480 const TargetLibraryInfo *TLI,
2481 const DominatorTree *DT) {
2482 return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT),
2486 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
2487 /// fold the result. If not, this returns null.
2488 static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
2489 // The type of the GEP pointer operand.
2490 PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType());
2491 // The GEP pointer operand is not a pointer, it's a vector of pointers.
2495 // getelementptr P -> P.
2496 if (Ops.size() == 1)
2499 if (isa<UndefValue>(Ops[0])) {
2500 // Compute the (pointer) type returned by the GEP instruction.
2501 Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1));
2502 Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
2503 return UndefValue::get(GEPTy);
2506 if (Ops.size() == 2) {
2507 // getelementptr P, 0 -> P.
2508 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
2511 // getelementptr P, N -> P if P points to a type of zero size.
2513 Type *Ty = PtrTy->getElementType();
2514 if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0)
2519 // Check to see if this is constant foldable.
2520 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2521 if (!isa<Constant>(Ops[i]))
2524 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1));
2527 Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const TargetData *TD,
2528 const TargetLibraryInfo *TLI,
2529 const DominatorTree *DT) {
2530 return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit);
2533 /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we
2534 /// can fold the result. If not, this returns null.
2535 static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
2536 ArrayRef<unsigned> Idxs, const Query &Q,
2538 if (Constant *CAgg = dyn_cast<Constant>(Agg))
2539 if (Constant *CVal = dyn_cast<Constant>(Val))
2540 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
2542 // insertvalue x, undef, n -> x
2543 if (match(Val, m_Undef()))
2546 // insertvalue x, (extractvalue y, n), n
2547 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
2548 if (EV->getAggregateOperand()->getType() == Agg->getType() &&
2549 EV->getIndices() == Idxs) {
2550 // insertvalue undef, (extractvalue y, n), n -> y
2551 if (match(Agg, m_Undef()))
2552 return EV->getAggregateOperand();
2554 // insertvalue y, (extractvalue y, n), n -> y
2555 if (Agg == EV->getAggregateOperand())
2562 Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val,
2563 ArrayRef<unsigned> Idxs,
2564 const TargetData *TD,
2565 const TargetLibraryInfo *TLI,
2566 const DominatorTree *DT) {
2567 return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT),
2571 /// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
2572 static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
2573 // If all of the PHI's incoming values are the same then replace the PHI node
2574 // with the common value.
2575 Value *CommonValue = 0;
2576 bool HasUndefInput = false;
2577 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
2578 Value *Incoming = PN->getIncomingValue(i);
2579 // If the incoming value is the phi node itself, it can safely be skipped.
2580 if (Incoming == PN) continue;
2581 if (isa<UndefValue>(Incoming)) {
2582 // Remember that we saw an undef value, but otherwise ignore them.
2583 HasUndefInput = true;
2586 if (CommonValue && Incoming != CommonValue)
2587 return 0; // Not the same, bail out.
2588 CommonValue = Incoming;
2591 // If CommonValue is null then all of the incoming values were either undef or
2592 // equal to the phi node itself.
2594 return UndefValue::get(PN->getType());
2596 // If we have a PHI node like phi(X, undef, X), where X is defined by some
2597 // instruction, we cannot return X as the result of the PHI node unless it
2598 // dominates the PHI block.
2600 return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : 0;
2605 static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
2606 if (Constant *C = dyn_cast<Constant>(Op))
2607 return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.TD, Q.TLI);
2612 Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const TargetData *TD,
2613 const TargetLibraryInfo *TLI,
2614 const DominatorTree *DT) {
2615 return ::SimplifyTruncInst(Op, Ty, Query (TD, TLI, DT), RecursionLimit);
2618 //=== Helper functions for higher up the class hierarchy.
2620 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
2621 /// fold the result. If not, this returns null.
2622 static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2623 const Query &Q, unsigned MaxRecurse) {
2625 case Instruction::Add:
2626 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2628 case Instruction::Sub:
2629 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2631 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
2632 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
2633 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
2634 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse);
2635 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
2636 case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
2637 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse);
2638 case Instruction::Shl:
2639 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
2641 case Instruction::LShr:
2642 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2643 case Instruction::AShr:
2644 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
2645 case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
2646 case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
2647 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
2649 if (Constant *CLHS = dyn_cast<Constant>(LHS))
2650 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
2651 Constant *COps[] = {CLHS, CRHS};
2652 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.TD,
2656 // If the operation is associative, try some generic simplifications.
2657 if (Instruction::isAssociative(Opcode))
2658 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
2661 // If the operation is with the result of a select instruction check whether
2662 // operating on either branch of the select always yields the same value.
2663 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
2664 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
2667 // If the operation is with the result of a phi instruction, check whether
2668 // operating on all incoming values of the phi always yields the same value.
2669 if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
2670 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
2677 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
2678 const TargetData *TD, const TargetLibraryInfo *TLI,
2679 const DominatorTree *DT) {
2680 return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, DT), RecursionLimit);
2683 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
2684 /// fold the result.
2685 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2686 const Query &Q, unsigned MaxRecurse) {
2687 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
2688 return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2689 return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
2692 Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
2693 const TargetData *TD, const TargetLibraryInfo *TLI,
2694 const DominatorTree *DT) {
2695 return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT),
2699 static Value *SimplifyCallInst(CallInst *CI, const Query &) {
2700 // call undef -> undef
2701 if (isa<UndefValue>(CI->getCalledValue()))
2702 return UndefValue::get(CI->getType());
2707 /// SimplifyInstruction - See if we can compute a simplified version of this
2708 /// instruction. If not, this returns null.
2709 Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
2710 const TargetLibraryInfo *TLI,
2711 const DominatorTree *DT) {
2714 switch (I->getOpcode()) {
2716 Result = ConstantFoldInstruction(I, TD, TLI);
2718 case Instruction::Add:
2719 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
2720 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2721 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2724 case Instruction::Sub:
2725 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
2726 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2727 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2730 case Instruction::Mul:
2731 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2733 case Instruction::SDiv:
2734 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2736 case Instruction::UDiv:
2737 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2739 case Instruction::FDiv:
2740 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2742 case Instruction::SRem:
2743 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2745 case Instruction::URem:
2746 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2748 case Instruction::FRem:
2749 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2751 case Instruction::Shl:
2752 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
2753 cast<BinaryOperator>(I)->hasNoSignedWrap(),
2754 cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
2757 case Instruction::LShr:
2758 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
2759 cast<BinaryOperator>(I)->isExact(),
2762 case Instruction::AShr:
2763 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
2764 cast<BinaryOperator>(I)->isExact(),
2767 case Instruction::And:
2768 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2770 case Instruction::Or:
2771 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2773 case Instruction::Xor:
2774 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2776 case Instruction::ICmp:
2777 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
2778 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2780 case Instruction::FCmp:
2781 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
2782 I->getOperand(0), I->getOperand(1), TD, TLI, DT);
2784 case Instruction::Select:
2785 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
2786 I->getOperand(2), TD, TLI, DT);
2788 case Instruction::GetElementPtr: {
2789 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
2790 Result = SimplifyGEPInst(Ops, TD, TLI, DT);
2793 case Instruction::InsertValue: {
2794 InsertValueInst *IV = cast<InsertValueInst>(I);
2795 Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
2796 IV->getInsertedValueOperand(),
2797 IV->getIndices(), TD, TLI, DT);
2800 case Instruction::PHI:
2801 Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT));
2803 case Instruction::Call:
2804 Result = SimplifyCallInst(cast<CallInst>(I), Query (TD, TLI, DT));
2806 case Instruction::Trunc:
2807 Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, DT);
2811 /// If called on unreachable code, the above logic may report that the
2812 /// instruction simplified to itself. Make life easier for users by
2813 /// detecting that case here, returning a safe value instead.
2814 return Result == I ? UndefValue::get(I->getType()) : Result;
2817 /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
2818 /// delete the From instruction. In addition to a basic RAUW, this does a
2819 /// recursive simplification of the newly formed instructions. This catches
2820 /// things where one simplification exposes other opportunities. This only
2821 /// simplifies and deletes scalar operations, it does not change the CFG.
2823 void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
2824 const TargetData *TD,
2825 const TargetLibraryInfo *TLI,
2826 const DominatorTree *DT) {
2827 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
2829 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
2830 // we can know if it gets deleted out from under us or replaced in a
2831 // recursive simplification.
2832 WeakVH FromHandle(From);
2833 WeakVH ToHandle(To);
2835 while (!From->use_empty()) {
2836 // Update the instruction to use the new value.
2837 Use &TheUse = From->use_begin().getUse();
2838 Instruction *User = cast<Instruction>(TheUse.getUser());
2841 // Check to see if the instruction can be folded due to the operand
2842 // replacement. For example changing (or X, Y) into (or X, -1) can replace
2843 // the 'or' with -1.
2844 Value *SimplifiedVal;
2846 // Sanity check to make sure 'User' doesn't dangle across
2847 // SimplifyInstruction.
2848 AssertingVH<> UserHandle(User);
2850 SimplifiedVal = SimplifyInstruction(User, TD, TLI, DT);
2851 if (SimplifiedVal == 0) continue;
2854 // Recursively simplify this user to the new value.
2855 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, TLI, DT);
2856 From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
2859 assert(ToHandle && "To value deleted by recursive simplification?");
2861 // If the recursive simplification ended up revisiting and deleting
2862 // 'From' then we're done.
2867 // If 'From' has value handles referring to it, do a real RAUW to update them.
2868 From->replaceAllUsesWith(To);
2870 From->eraseFromParent();